As an alterantive to the Thermarest range... I use an Artiach Skin Mat, and I find it's really comfortable. I've got a full length one too, like most people here, I'd say that the extra bit of weight is not worth the hit on the comfort.
Not too cheap tho, but does come with an oddly intriguing strangely sticky/not sticky surface (!). Might be a bit more fragile than some, but inside my bivi bag, which is on a bit of ripstop, it seems to have been ok so far. It's been better having had a bit of time to self-inflate, but I'd think they are all like that, just like shaking your sleeping bag out in plenty of time too ...
Not too cheap tho, but does come with an oddly intriguing strangely sticky/not sticky surface (!). Might be a bit more fragile than some, but inside my bivi bag, which is on a bit of ripstop, it seems to have been ok so far. It's been better having had a bit of time to self-inflate, but I'd think they are all like that, just like shaking your sleeping bag out in plenty of time too ...